STRONG-ACID, CARBOXYL GROUP STRUCTURES IN FULVIC-ACID FROM THE SUWANNEE RIVER, GEORGIA .1. MINOR STRUCTURES

An investigation of the strong-acid characteristics (pK(a) 3.0 or less ) of fulvic acid from the Suwannee River, Georgia, was conducted. Quan titative determinations were made for amino acid and sulfur-containing acid structures, oxalate half-ester structures, malonic acid structur es, keto acid structures, and aromatic carboxyl-group structures. Thes e determinations were made by using a variety of spectrometric (C-13-n uclear magnetic resonance, infrared, and ultraviolet spectrometry) and titrimetric characterizations on fulvic acid or fulvic acid samples t hat were chemically derviatized to indicate certain functional groups. Only keto acid and aromatic carboxyl-group structures contributed sig nificantly to the strong-acid characteristics of the fulvic acid; thes e structures accounted for 43% of the strong-acid acidity. The remaini ng 57% of the strong acids are aliphatic carboxyl groups in unusual an d/or complex configurations for which limited model compound data are available.